ABC | Volume 112, Nº5, May 2019

Guideline Brazilian Fetal Cardiology Guidelines – 2019 Arq Bras Cardiol. 2019; 112(5):600-648 upper mediastinum, obtaining 6 planes, as shown in Figure 2.1. 2.2.1. Step 1 – 1 st Level: Evaluation of the Abdomen to Identify the Abdominal Aorta and the Inferior Vena Cava This is a transverse view of the fetal abdomen, in the subdiaphragmatic region, and helps to determine the abdominal situs. Before starting, it is necessary to identify the right and left sides of the fetus, according to the fetal presentation; the stomach should be on the fetal left side and the liver on the right. Furthermore, the descending aorta should be seen posterior and to the left, close to the spine, and the inferior vena cava anterior and to the right, within the hepatic parenchyma. 2.2.2. Step 2 – 2 nd Level: Four Chamber View This view is obtained with a transverse scan of the fetal thorax, immediately above the diaphragm. The heart should occupy one third of the thorax, the greater part being in the left hemithorax, with the apex turned to the left. The interventricular septum should be at an angle of approximately 45 th with the midline. The first step for fetal cardiac analysis is the identification of the spine. Opposite to the spine is the anterior wall of the thorax, or sternum. Below is the right ventricle, which is characterized by the moderator band and the tricuspid valve, located a few millimeters displaced to the apex. Returning to the spine, the descending aorta is seen anteriorly as a circle in the mediastinum and, in front of it, is the left atrium. The left atrium is close to the descending aorta and can be identified by the characteristic movement of the foramen ovale flap. Other intracardiac structures, such as the right atrium and the left ventricle, may then be analyzed. They should have dimensions similar to those of the contralateral chambers. The atrioventricular valves should be analyzed in relation to their movement and size of their valve annulus. Figure 2.1 – Standardization of fetal heart screening, scanning the fetal vessels and heart from the infradiaphragmatic region towards the cranium. There are 6 levels, being the first exactly below the diaphragm, which allows the identification of the descending aorta and inferior vena cava; second, the four-chamber view; third, left ventricular outflow tract; fourth, right ventricular outflow tract; fifth, three vessel view, and, sixth, three vessel and trachea view. Ao: Aorta; AoA: aortic arch; Asc: ascending; DA: ductus arteriosus; IVC: inferior vena cava; LA: left atrium; LV: left ventricle; PA: pulmonary artery; RA: right atrium; RV: right ventricle; RVOT: right ventricular outflow tract; S: stomach; Sp: spine; SVC: superior vena cava; T: trachea. S IVC SVC SVC RA PA Sp Sp Sp Sp Sp Sp RV LV RV LV LA LA RVOT PA AoA 605